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Old 01-28-2003, 11:16 AM - Thread Starter
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What is the difference between ansi lumens and lumens?

There are some projectors with 800 lumens that cost more than a projector with 1400 ANSI lumens. Why is that?

I thought ANSI lumens is the most accurate and best rating of light projection?
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Old 01-28-2003, 12:07 PM
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ANSI just requires the use of the same test protocol so that comparisons between projectors are apples to apples. This makes the numbers more useful. As to why projectors cost more lumens is only a single part. Look at CRT projectors very low lumens very high cost.

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Old 01-28-2003, 01:26 PM - Thread Starter
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Quote:
Originally posted by hpalmer
ANSI just requires the use of the same test protocol so that comparisons between projectors are apples to apples. This makes the numbers more useful. As to why projectors cost more lumens is only a single part. Look at CRT projectors very low lumens very high cost.

HPalmer
What do you mean CRT projectors very low lumens very high cost?
I'm not clear on that. Thanks for the information.
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Old 01-29-2003, 06:30 AM
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CRT Projectors cost a lot (at least new) and are not bright.
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Old 01-29-2003, 06:45 AM
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CRT projectors are typically measured in "peak white" lumens. They cannot maintain full brightness over the entire screen indefinitely but can have short bursts of brightness.

This is analogous to your amplifier rated at "100 watts peak" but only "50 watts RMS".

The ANSI lumen test uses an entire white screen output, so CRT projectors will have moderate peak white lumens (600-1000) but poor ANSI lumens (150-300).

For LCD projectors, both ANSI and peak white are the same.

A great descripion I found is here...

http://barco.com/projection_syst...ces/advice.asp
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Old 01-29-2003, 09:47 AM
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for an ansi lumen measurement, you have a test pattern with 4 white squares and 4 black squares, and the display must be adjusted so that all squares are visible. (proper contrast and brightness) then you measure.

just hanging out, rollin with the flow.
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Old 01-29-2003, 10:27 PM
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Quote:
Originally posted by Dizzman
for an ansi lumen measurement, you have a test pattern with 4 white squares and 4 black squares, and the display must be adjusted so that all squares are visible. (proper contrast and brightness) then you measure.
This is correct, but what also should be noted is that ANSI lumens are a 9-point average of the image brightness. To get plain lumens you can measure the center brightness (where the image is typically brightest) and divide by the screen area, always yielding a higher number than ANSI testing would give you.
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